Modelling by the Telethon Kids Institute and Curtin University suggests WA is about halfway through its current COVID-19 Omicron outbreak, with about half a million more West Australians expected to be infected with the virus by the end of June.
As of yesterday, the state had recorded 425,704 COVID-19 cases since the pandemic began.
Lead researcher Ewan Cameron said his team's modelling showed that figure would double before the outbreak was over.
He said that doubling would happen in a much shorter period of time and said the easing of restrictions had no doubt played, and would continue, to play a role.
"We believe that the infection rate over the next two to three weeks will be perhaps the highest it has been throughout the outbreak," Dr Cameron said.
"The gradual easing of restrictions has led to an increased rate of transmission. We have both the mask mandate being removed as well as, before that, the change to the close contact definition.
"On the other hand, Western Australians have been very diligent at seeking testing, and so the detection of cases and the sort of isolation of cases during the symptomatic phase has been high, which has helped to slow or reduce the possible impact of removing the mask mandate."
WA to see 'gradual tail' rather than rapid drop in cases
Yesterday Western Australia reported a new record in COVID infections, breaking through the 10,000 daily case mark for the first time.
But according to Dr Cameron and his team's modelling, that figure is not expected to balloon significantly in the weeks ahead.
Dr Cameron said the modelling suggested daily case numbers would remain above 10,000 for the next couple of weeks before beginning to drop by the end of May and through June.
"This would not be as rapid a drop-off as has been seen in some other states, but more of a gradual tail."
Very young and old most likely to be infected
The Curtin University and Telethon Kids Institute team behind the "real-time" modelling created a new software tool to build a "virtual WA" based on the state's unique geography and demographics.
It used data from a range of sources, including the Australian Bureau of Statistics, Landgate and Google to create the simulations.
Researchers involved said that allowed them to capture real interactions and provided the most detailed COVID-19 modelling ever applied to an Australian outbreak.
According to the modelling, the majority of people who have already had COVID-19 in this outbreak are in the 18-35 age group, for which 59 per cent of projected infections have already taken place.
A close second was the 35-65-year-old cohort, for which 56 per cent of infections have already occurred.
However, moving forward, the youngest and oldest age groups are expected to account for more infections in the second half of the outbreak.
"The zero to 18-year-old age group is only just past its halfway point at 51 per cent of projected infections, and the 65-plus age group [is at] 53 per cent," Dr Cameron said.
"We usually see older people infected later in these outbreaks, and of course, people over 65 are most at risk of becoming seriously ill or dying with COVID-19.
"We've seen this in other states and around the world. These later infections of older people can cause a spike in deaths towards the end of the outbreak, so it's really important that people in that age group take extra precautions to protect themselves."
Deaths to reach 300 by end of June
So far in WA, 157 people have died with COVID, the vast majority of them from this current outbreak.
Dr Cameron said the number of deaths was expected to peak around 300 by the end of June with the modelling showing it was unlikely to climb much higher.
Yesterday, the number of people in hospital with the virus jumped to 271 from 242 the day before, a figure the WA president of the Australian Medical Association Mark Duncan-Smith said was concerning.
Dr Duncan-Smith has repeatedly said any more than 350 people in hospital with COVID at any one time would stretch the health system beyond breaking point, but Dr Cameron said the modelling showed that was unlikely.
"We anticipate that hospitalisations and ICU rates will continue to be at a high level but will [only] slightly increase along with this increase in cases," he said.
"ICU and hospitalizations do lag [behind] case numbers so we won't expect to see those upticks this week but into the middle and end of next week.
"Our modelling at this stage suggests that we will remain well below that level of 350 beds occupied."
